Field of the Invention
The present invention relates to the field of manufacturing technologies of semiconductor power devices, and more particularly to a method for manufacturing a split-gate power device.
Description of Related Art
With the continuous development of microelectronics technologies, semiconductor power devices are gradually replacing bipolar devices to become the mainstream of development of current power devices, for advantages such as high input impedance, low loss, fast switching speed, no secondary breakdown, wide safe operating area, good dynamic performance, being easy to be coupled to a front pole to achieve a large current, and high conversion efficiency. A split-gate power device can reduce parasitic capacitance between a control gate and a drain region, decrease the dynamic power consumption of a device and increase the switching speed, and has become a preferred structure of a semiconductor power device. An existing typical method for manufacturing a split-gate power device includes: forming a control gate groove in a substrate epitaxial layer 100, and forming a control gate 105 at two sides of the control gate groove respectively by using a process of depositing and then etching-back a conductive layer, as shown in FIG. 1a; next, covering the control gates 105 to form insulating film dielectric layers 201 by using a process of depositing and then etching-back an insulating film, and etching the substrate epitaxial layer along the edges of the insulating film dielectric layers 201 to form a split-gate groove, as shown in FIG. 1b. 
The existing typical method for manufacturing a split-gate power device has the following problems. Firstly, the lateral width of the control gates 105 is small, so that the difficulty in etching of control gate contact holes is increased; and secondly, in the process of forming the insulating film dielectric layers 201 by using an etching-back method, parts of the insulating film dielectric layers above the control gates 105 are easily etched, so that the control gates 105 are hard to protect. Thus, the manufacturing process of the split-gate power device is hard to control, and the yield is low.